Changing text field colour, when entering/entered information in a pdf

Help!! I am trying to design an interactive pdf form. The text fields are usually a light bluish/purple colour, but when I enter a curser or go to type in a field it turns white! Sometimes it’s hard for the users to see where they are up to in the form. Is there a way that when the field is active and entering information it can be a different colour, and in addition to this, is there a way to have fields that have been entered previously (but inactive, no curser present) to be another colour??

I have never learnt javascript, but found this code online…

On page open
var arh = app.runtimeHighlight ;
var arhCol = app.runtimeHighlightColor ;
app.runtimeHighlight = true ;
app.runtimeHighlightColor = color.gray;

On page close
app.runtimeHighlight = arh ;
app.runtimeHighlightColor = arhCol ;

This turns the fields grey, but doesn’t solve my problem of changing colour when a field is actively having information entered, and that have previously had information entered.

Very big thank you in advance!